NEW ULM, Minn. — Authorities nationwide are on the lookout Wednesday for a mother and her 13-year-old cancer-stricken son who fled after refusing the chemotherapy that doctors say could save the boy’s life.

Colleen Hauser and her son, Daniel, who has Hodgkin’s lymphoma, apparently left their southern Minnesota home sometime after a doctor’s appointment and court-ordered X-ray on Monday showed his tumor had grown.

Brown County District Judge John Rodenberg, who had ruled last week that Daniel’s parents were medically neglecting him, issued an arrest warrant Tuesday for Colleen Hauser and ruled her in contempt of court. Rodenberg also ordered that Daniel be placed in foster care and immediately evaluated by a cancer specialist for treatment.

The boy’s father, Anthony Hauser, testified he didn’t know where his wife and son were but had made no attempt to find them. He testified he last saw his son Monday morning, and he saw his wife only briefly that evening when she said she was leaving “for a time.”

As of Wednesday morning, the mother and son still had not been found, said Carl Rolloff, a sheriff’s dispatcher.

Officials distributed the arrest warrant nationwide. Brown County Sheriff Rich Hoffman said Tuesday that investigators were following some leads locally, but declined to elaborate.

“It’s absolutely crazy. It’s very disappointing,” James Olson, the attorney representing Brown County Family Services. “We’re trying to do what’s right for this young man.”

A message left at the Hauser home in Sleepy Eye early Wednesday wasn’t immediately returned. But in an interview Tuesday evening with the Star Tribune of Minneapolis, Anthony Hauser said he knew places where his wife might have gone but he did not know where she was.

He said he and his wife had a plan for Tuesday’s hearing, and he was a “bit disappointed” she didn’t follow it. “We were going to present a treatment plan to the court. If they didn’t go with it, we would appeal it,” he told the newspaper.

He said he isn’t against chemotherapy, but would prefer that it be given less frequently and along with alternative medicine. “I know many people around here who have had cancer, they did the chemo, it would come back,” Hauser told the newspaper. “They did the chemo again and again and they are all in the grave. Chemo isn’t foolproof.”

Daniel’s Hodgkin’s lymphoma is considered highly curable with chemotherapy and radiation, but the boy quit chemo after a single treatment. With his parents, he opted instead for “alternative medicines,” citing religious beliefs. That led authorities to seek custody. Rodenberg last week ruled that Daniel’s parents were medically neglecting their son.

The judge has said Daniel, who has a learning disability and cannot read, did not understand the risks and benefits of chemotherapy and didn’t believe he was ill.

The Hausers are Roman Catholic and also believe in the “do no harm” philosophy of the Nemenhah Band, a Missouri-based religious group that believes in natural healing methods advocated by some American Indians.

Colleen Hauser testified earlier that she had been treating his cancer with herbal supplements, vitamins, ionized water and other natural alternatives.

The founder of Nemenhah, Philip Cloudpiler Landis, said it was a bad idea for Colleen Hauser to flee with her son.

“She should have gone to court,” Landis said. “It’s how we work these things out. You don’t solve anything by disregarding the order of the judge.”

Anthony Hauser now agrees that Daniel needs to be taken back to a doctor for re-evaluation for the best treatment, said Calvin Johnson, an attorney for the parents.

The family’s doctor, James Joyce, testified by telephone that he examined Daniel on Monday, and that an X-ray showed his tumor had grown to the size it was when he was first diagnosed.

“He had basically gotten back all the trouble he had in January,” the doctor said.

Joyce testified that he offered to make appointments for Daniel with oncologists, but the Hausers declined. He also said he tried to give Daniel more information about lymphoma but the boy, his mother and lawyer Susan Daya left in a rush.

“Under Susan Daya’s urging, they indicated they had other places to go,” Joyce said.

Daya did not immediately respond to a call Tuesday from The Associated Press. The court also tried to reach her during the hearing, but got no answer.

In his ruling last week, Rodenberg wrote that he would not order chemotherapy if Daniel’s prognosis was poor. But if the outlook was good, it appeared chemotherapy and possibly radiation would be in the boy’s best interest, he wrote.

Daniel’s lymphoma was diagnosed in January, and six rounds of chemotherapy were recommended. He and his parents sought other opinions, but the doctors agreed with the initial assessment.